Elastic tire.



P. W. PRATT.

PLASTIC TIRE;

APPLIQATION FILED JUNE 1l, 1910.

Patented sept. 3,1912;

stituting the tread face ofthe tire.

elastic tire.

invention is embodied in the part repre- .nrnnr carica..

l PHILIP W. PRATT, 0F BOSTON, MASSACHUSETTS.,

nnasrrc rms.

To all whom t may concern Be it blown ,that I, PHILIP WATSON' PRA'LT, of Boston, vin the county of Suffolk? and'State of' Massachusetts, have invented certain new and useful Improvements inf Elastic Tires,. of whichV the following is a. specification.

`This invention has special reference tothe tread portion 'of a pneumatic o r other The invention is embodied in a tire tread which, as here shownfforms a part, of the shoe of a pneumatic tire.

The invention has for its'object to pro-1 vide a tire tread adapted to resist wear tol a greater degree than4 treads heretoforel known, and also to furnish a desirable degree of resistance to side slip or skidding.

The invention consists in improvements, which I will now proceed to describe andi claim.

Of the accompanyin drawings which form a part of this spec1fication,-Figure 1 represents a transverse section of a pneumatic tire shoe embodying my invention. Fig. Q'represents an enlargement of a portion of Fig. 1. Figs. 3 and 4l represent perspective views of portions of the layers of textile fabric hereinafterreferred to. Figf represents a section on line 5*-5 of Fig. 1, but not showing the fabric as plaited. Fig. 6 represents a plan view of a portion of my improved tread as it would appear if flattened outs' Similar reference characters indicate the same or similar parts in all the figures.

In Fig. l of the drawings I have shown partly by dotted lines a cross section of a pneumatic tire shoe of the clencher type to which a tread embodying my invention is applied, the body portion of the shoe including the means forengaging the Wheel` rim, belng represented by dotted lines and forming no part of the present invention. My

sented by full lines in Fig. 1, said part, in this embodiment of the invention, being a tread band formed to be applied to the body portion of the shoe and vto surround the sarge, the outer surface of said tread Coln- T 1e said part comprises a facing 13, of frictioned textile fabric, and a backing 14,

Specification of Letters atent. l Application filed .Tune 11, 1910. lSerial Eo. 566,331'.

which for convenience, I will term frubber,

Patenteusept. 3, 191,2.

l the material of which the backing is made being elastic and containing the percentage of rubber which is l,usual in so-called rubber tires;

The fabric of which the facing is made is I preferably duck or canvas, frictioned, or in 4 other words, treated with unvulcanized rubber in Solution. The fabric may be incorporated withv the rubber backing by suitable molding and vulcanizing operations which need not be herein described. The molds are so shaped, however, that the tread will be formed with elongated ridges 15 which extend length-wise of the periphery of the tread, the said ridges having ends, eachl formed by two inclined faces 1G.

As shown in Fig. 6, the projections are preferably arranged in two series of groups7 the projections of one series being longer than those of the other and the ridges 15 of the said projections breaking joint with each other. The ridges constituting elongated projections extending lengthwise of the periphery of the tread, are particularly adapted to prevent side slip or skidding of the tire of which the tread fornisla part.

It will be observed that the-projections formed by corrugating the text-ile fabric facing are lled and supportedinternally by the rubber backing 14e, so that the said projectons are permane t and ,durable Owing to -tieY fact that the corrugated facing is 'composed of textile fabric, the durability thus disposed in a series of narrow stretches set w'sdg'ewise to the tread surface, said stre'ches being connected by the bends or folds of the fabric. The fabric may be transversely stitched as at 20. This for* mation of the fabric practically inbreasestits los i formed into a plurality of narrow folds 17, `,asishown by Figs. 3 and 4, the fabric being thickness and causes the facing to present the ends of many of its threads at the tread surface after the necks connecting the outer edges of the narrow stretches are Worn away, said stretches being caused to. adhere closely'to each other by the frictioning material which is applied to the fabric before it is folded or plaited. The folds of one layer preferably extend cross-Wise of the folds of the other layer, as indicated by Figs. 3 and t.

ln assembling the parts, a layer 18 of unvulcanized rubber is interposed between the outer and inner fabric layers, the outer layers then being placed in contact with the corrugated facing of the female mold member.

By the use of the fabric incorporated into the thread as described, the conformation of the ridges is preserved during use, and Wear isV reduced to the minimum. That'is the shape of the ridges Will remain unchanged for a far greater period when the fabric is incorporated therewith, than if it is not employed. The fabric is Wear-resisting, and moreover, serves as areinforee to increase the durability of t-he ridges and preserve their shape under pressure of use. In other words, When the portion of the tread as shown at the top of F ig. l is bearing on the ground, and the automobile is heavy so that the pneumatic tire Will yield, there is not much change in the shape of the tread itself, because of the reinforcing material employed, and the thickness of the tread. Ordinarily, the tread portion of a tire having my improved structure therein will retain its transversely curved form although the transverse shape may, under pressure', be changed to a curve of-grcater radius. At any rate, the tire tread remains curved longitudinally and laterally to conform to thel exterior of a pneumatic tire. And the ridges extend lengthwise of the periphery of the tread, and as best sho\vn in Fig. (5, the ridges are formedl 1n groups or series, the apexes of the ridges of one series being in longitudinal alinement with the bottoms of the recesses between the ridges of the next series. As best shown in Fig. l, all of the ridges have angular apexes and the bottoms of the reccsses between the ridges are angular'. rlhis fact, in connection with the transverse or lateral curvature of the tread causes the tread to present a plurality of fiat surfaces which face in different directions and all of which are tangential to the tire. There are always present one or two sharp apexcs to bear on a very slightly plastic road surface, with almost horizontal flat surfaces .il each side of the lcenter to resist tendency v to force the wheel or its tire into a rather muddy surface, while the extreme side plum-s toward the two margms of the tread,

Will present obstructions to sliidrdino, in case the roadway is very muddy.

The project-ions of the rubber backing let enter and are vulcanized to the internal corrugations of the Wear-and-slip-resisting facing 13. Said projections are higher than the intermediate depressed portions of the. facing, the stretches of the facing forming the sides of the corrugations, being firmly held in inclined positions by the projections of the backing to Which they are vulcanized.v The Wear on the facing incidental to use is therefore not sustained at once by all portions of the tread surface but is sustained first by the apexes of the corrugations.

vWhen these apexes have been Worn Aaway to the apexes of the rubber backing projections, the intermediate depressed portions of the facing remain unworn and a tread surface is formed composed in part ofa multiplicity of ends 0f threads of the plaited fabric exposed by Wear, and in part by the exposed portions of the rubber backing projections. The fabric portions of this tread surface resist skidding and are held inplace by the rubber portions lying beside them. This condition prevails until the tread has been Worn down practically to the bases of the projections of the rubber backing. During the entire period of this Wear a consid.- erable extent of non-skidding tread surface is continuously present', as may be understood by reference to Fig. 2, Where the lines -m, y-y, and z-c, indicate successive degreesof Wear.

I claim l. A tire tread curved longitudinally and laterally to form the tread surface of a pneumatic tire and composed of wear-andsl ip-resisting facing of frictioned textile fabric, and a backing ofvrubber vulcanized to the said facing, the facing land backing be,- ing molded to formy elongated staggered external corrugations having angular apexes and arranged longitudinally of the tread, the apexes of the backing projections'being above the depressions in the corrugated facing, so that the backing holds the depressed portions of the facing after the apexes of the facing corrugations have been Worn away.v

2. A tire tread curved longitudinally and laterally to form' the tread surface of a pneumatic tire, and composed of a wearand-slip-resisting facing of frietioned textile fabric, folded or plaited to form a series of stretches extending edgewise to the tread face, and a backing of rubber vulcanized to the said facing, the facing and backing being molded to form elongated staggered external corrugations having angular apexes and arranged longitudinally of the tread, the apexes of the backing projections being above the depressions in the corrugated facing, so that the backing holds the depressed portions of the facing after the In testimony whereof I have affixed my apeXes of the Ifacing corugfatiols have been signature, in presence of two Witnesses. worn away, t e remova o sai apeXes by Wear causing the exposure of a multiplicity PHILIP W RAiJST 5 of thread ends which form non-skldding Witnesses: tread portions alternating with exposed fab- C.4 F. BROWN, rio-holding portions of the rubber backing. P. WJ Pnzzm'r. 

